Process of improving the magnetic qualities of iron-silicon alloys.



UNITED STATES PATENT OFFICE- ROBERT A. HADFIELD, OF SHEFFIELD, ENGLAND. PROCESS OF IMPROVING THE MAGNETIC QUALITIES 0F IRON-SILICON ALLOYS.

To all zuho1n it may concern:

Be it known that I, ROBERT A. HADFIELD, a subject of the King of Great Britain, residing at Parkhead, Sheffield, England, have invented a certain new, and useful Improvement in Processes for Im roving the Magnetic Qualities of Iron ilicon Alloys, of which the following is a specification.

In United States Letters Patent No.

745,829, granted to me December 1, 1903, I

have set forth a method of producing a magnetic material of high permeability and low,

The alloy employed must be one low in carbon and manganese and having as its principal constituents iron, together. with from one to five per cent. of silicon or any element or elements equivalent to silicon in the same combination. The com 'osition and range of ingredients of such an al oy may be as follows: iron-silicon from one to five per cent., manganese up to five-tenths of one per cent., and carbon up to fifteen-hundredths of one per cent. I carry my process into effect byfirst heating said alloy to a temperature above a critical point (hereinafter defined) and then cooling said heated alloy slowly. A resulting product is obtained having greater permeabilit and a lower hysteresis quality than is exhibited by Specification of Letters Patent.

Application filed February 27, 1906. Serial No. 303,149.

Patented Nov. 2'7, 1906.

the best commercial Swedish charcoal-iron. I

other point ensues at which another molecular change occurs. The term critical oint in the claims 'means the point of 'gher temperature of the two above-noted and corresponds and approximates to the 900 centigrade point in the case of pure iron, which is the lower limit of its so-called gamma state.

In practice I have satisfactorily performed my process by subjecting the said alloy to a temperature of 1,050 centigrade and then cooling it at the approximate rate of ten degrees per hour.

' I claim l. The process of increasing the permeability and reducing the hysteresis action of an alloy low in carbon and manganese and containin iron with from one to five per cent. of si icon, which consists in heating the said alloy to a temperature above its critical point and then subjecting it to cooling only.

2. The process of increasing'the permeability and reducing the hysteresis action of an alloy low in carbon and manganese and containing iron with from one to five per cent. of silicon, which consists in heating the said alloy to a tem erature' above its critical point and then Sub eoting it to slow cooling.

In testimony whereof I have affixed my signature in presence of two witnesses.

ROBERT A. HADFIELD. Witnesses G. H. HEMSOLL, E. RODGERS. 

